While fans of the iPhone 5 are still waiting patiently for T-Mobile to offer the smartphone, a leaked roadmap shows that the U.S. carrier is set to get its second Windows Phone 8 device: a new mystery smartphone, Nokia Flame, on April 24.

The Nokia Flame smartphone will allegedly pack in 4G capabilities and will run on the latest Windows Phone 8 platform. The new information is courtesy folks at TmoNews, who managed to lay their hands on the leaked roadmap.

"A brand new T-Mobile roadmap just hit our inbox and it appears the next Windows Phone 8 device has been uncovered for T-Mobile. Unfortunately, if the "Flame" codename is the same "Flame" codename discovered last September, there's not a lot to get excited about," reported TmoNews.

According to the report, the Nokia Flame could be the same handset which was spotted last year on a T-Mobile roadmap. At the time, the specs suggested that the Flame would be an entry-level handset, featuring a 4-inch display, a 1GHz dual-core processor, 512MB of RAM, and only 4GB of on-board storage (expandable via microSD slot). Additionally, the Flame was also rumored to sport a 5-megapixel rear-facing camera.

Indications are that the WP8-powered Nokia Flame could launch on T-Mobile's monthly service. With rival AT&T touting the high-end Lumia 920 and Verizon speculated to get a Lumia 920 variant, T-Mobile currently only offers the Lumia 810 (and the older Windows Phone 7.8 Lumia 710) and needs to pull up its socks and offer a high-end WP8 handset soon to stay in the race.

With the Nokia Flame conjectured to hit T-Mobile stores on April 24, we'll soon know if the fabled WP8 device from the carrier can eat into competitors' share.